Consumer products such as electronic devices are typically made from multiple pieces that are assembled together during a manufacturing process. The pieces can be made of different materials such as metal, plastic, glass, etc. For instance, an electronic device can have a metal housing with a glass window or screen as well as plastic components fitted into certain regions of the metal housing. For aesthetic reasons, usually it is desirable for the pieces to be joined together in a flush manner such that the resultant product has no visible or tactile gaps between them.
Since consumer products are generally manufactured in mass, it can be difficult to produce individual pieces that fit together in a seamless manner. In particular, machining of parts involves tolerances, which inevitably introduces errors in the dimensions of the pieces. If two machined pieces are fit together, the resultant gap will include the sum of the manufacturing error from the nominal design of the two components. Additionally, other factors such as part handling, stress relief during subsequent processing and environmental conditions can change the shape of the parts prior to assembly. The result is individual pieces that have different dimensions that do not fit seamlessly together.